<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        *{
            box-sizing: border-box;
        }
      div.article{
          width: 200px;
          height: 300px;
          background-color: black;
          margin: 0 auto;
      }
      div.top{
          width: 200px;
          height: 200px;
          padding: 20px;
          animation: outer;
          animation-iteration-count: infinite;
          animation-duration: 5s;
          animation-timing-function: linear;
      }
      div#outer{
            height: 100%;
            border: 3px solid #ccc;
            border-radius: 50%;
            padding: 20px;
            animation: inner;
            animation-iteration-count: infinite;
            animation-duration: 5s;
            animation-timing-function: linear;
      }
      div#inner{
          height: 100%;
          border: 10px solid #ffff;
          border-radius: 50%;
      }
      div.text{
          color: #ffff;
          text-align: center;
      }
      /*外圆*/
      @keyframes outer{
          25%{
            padding: 10px;
          }
          50%{
              padding: 20px;
          }
          100%{
              padding: 20px;
          }
      }
      /*内圆*/
      @keyframes inner{
          25%{
              padding: 30px;
          }
          50%{
              padding: 20px;
          }
          75%{
              padding: 32px;

          }
          100%{
              padding: 20px;
          }
      }
    </style>
</head>
<body>
    <div class="article">
        <div class="top">
            <div id="outer">
                <div id="inner"></div>
            </div>
        </div>
        <div class="text">hi!</div>
    </div>
</body>
</html>